Lamp socket



Patented Dee. 14., 1948 George H. Goble, Haddon Heights, N. J., assignor to Radio Corporation oi America,` a corporation oi Delaware Application October 2, 1946. Serial No. 700,809

` 4 0mm. (ci. usf-ses) This invention relates to lamp sockets for preiocused electric lamps and, considered from one aspect, constitutes an improvement upon the invention more broadly claimed in copending application Serial No. 694,038 to Sten E. Bartelson, illed August 30, 1946.

Sockets for pre-focused lamps are usually provided with a plurality of spring-biased pins which engage the base of the lamp and hold it in a position whereat the illament is in register with the optical system which the lamp is designed to serve. The removal of a lamp ".from such a socket can be an extremely troublesome operation. particularly when the lamp is hot and is mounted in a .motion picture projector or other crowded cabinet. Bartelson in his above identifled disclosure describes how the foregoing di!- flculty may be overcome by the provisionjjoi a socket containing a movable inner-base to which the spring-biased retainingpins are atllxed and by the provision of a lever arm, which extends from said base to the exterior of the socket, for relieving the retaining pins of their claxnping action while the lamp is being removed from, or inserted in, the socket. "E,

The present invention is concerned primarily with pre-focused lamp installations of the'type wherein it is necessary or expedient to providel the socket not only with lamp-retaining springs but with a plurality of spring-type electrical contacts as well. In applying Bartelsons'lever to lamp sockets of this latter type instances have arisen wherein the lamp remained tight in its socket (although relieved of the clamping force of its retaining pins) because no provision was made for relieving the lamp oi.' the re ning force which is applied thereto by the spry ngs on the electrical contacts. In such installations this additional force was found to comprise about 40% of the total retaining force applied to the lamp.

Accordingly, the principal object of the present invention is to provide an improved lamp socket of the type incorporating not only springbiased lamp-retaining pins, but spring-biased electrical contacts as well, and one characterized by the provision. of means for relievingv the forces normally exerted upon the lamp by Vall of said springs, whereby to facilitate the removal or the insertion of the lamp.

The invention will be described in connection with the accompanying drawing wherein:

Fig. 1 is a side elevation partly in section of a pre-focused lamp assembly including a lock socket having a lever actuated releasing mechanism constructed in accordance with the principle of the invention. c

Fig. 2 is' a sectional view taken along the line II--II of Fig. l,

Figs. 3 and 4 are views similar to Fig. 1 but showing the lever in diierent operating positions and,

Fig.' 5 is a sectional view, taken on the line V-V oi IFig. 3, ofthe bottom of the socket of Figs. 1-4, showing details of the spring-actuated electrical contacts for the lamp,

In the drawing, wherein like reference characters are applied to the same parts in all iigures, i designates generally a casting formed of metal, porcelain or other suitably rigid material which serves as a support for an optical system comprising a lens 2, an electric lamp` I and a socket 4 which holds the lamp-in a position whereat itsA hoirzontally disposed filament l-is inregister with the lens 2. The metal base of the lamp is of a conventional type and'comprises d which are-mounted, in-a manner later described. on the socket I. a K' The lamp socket comprises an upper base in the form ot an. annular metal disk Il which is immovably secured to the pedestal I and a dependent lower base i2 of similarshape which is supported for vertical movement in register with. the upper annulus upon the' lower ends of the locking pins lila, Illb and ille. The said pins Illa etc. extendupwardly through suitably spaced clearance holes in the annulus or disc li I' and, terminate thereabove in pinheads which limit the extent o f the downward movement of the lower annulus I2. The pins lila etc. and hence the lower annulus I2 are biased in the downward directionl by means of springs |3a, llband` I3c, which are wrapped, respectively, about the said pins in the space between the upper and lower annular discs. The lower annulus I2 has a dependent integral tubular socket portion I4 whichis designed to receive the tubu.'

lar base 8 of the lamp. This socket portion il contains an insulating insert I! which "serves as These leads I6 and I8' are biased to bear upwardly against the lamp terminals 1 and 1 by springs I1 and I1' which are wrapped, respectively,gabout the said movable leads.

The lamp 3 is locked in the socket 4 by aligning the bayonet slots 9a etc. in the flange 8 with the retaining pins Ia etc., then entering the dependent tubular portion 6 of the lamp base through the central holes in the upper and lower discs II and I2 into the dependent portion I4 of the socket and, nally, twisting the lamp to bring the reduced neck portions `of the bayonet slots into register with the pins so that the retaining force of the springs I3a etc. is exerted upon the ange 8 of the lamp and the springs I1 and I1' on the filament leads I6 and IB' evert their force against the electrical terminals 1 and 1 on the bottom of the lamp..

yWhen the lamp 3 and its socket 4 are of the typeabove described the twisting force required to lock and unlock the lamp must be suilicient to overcome not only the clamping force applied to the tube flange 8 by the spring biased pins I 0a etc. but also to overcome the retaining force which is applied to the lamp base 6 through its terminals 1 and 1' by the spring biased electrical contacts I6 and I6. If the springs, or any of them, are stii through long non-use, or the lamp bulb is fragile or hot it would be diflicult to apply the twisting force required to unseat the lamp.

The foregoing difliculty is overcome, in accordance with the present invention, by the provision of a lever of novel constructionwhich relieves the electrical contacts 1 and 1 (and hence the base 6 of the lamp) as well as the retaining pins Illa etc. (and hence the lamp flange 8) of the forces exerted thereon by the separate groups of spring |3a etc. and I1, I1'.

In the embodiment of the invention which has been selected for illustration there is a short L-shape lever 20 aixed, at the end of the short arm of the L, to the lower end of each of the two electrical leads I6 and I6. These L-shape members 20 carry a lever 2| which is pivoted on an electrically insulating pin or screw 22 which extends between the vsaid members at the end of the upstanding arm of the L. One end 2Ia of this lever 2| is free to bear against the underside of the vertically movableV lower annulus I2 of the socket and the opposite end 2 Ib or handle of the lever extends a convenient distance beyond the periphery of the socket. There is a hole 2 I c intermediate the ends 2Ia, 2lb of the lever 2| through which a fulcrum pin or screw 23 extends. This pin 23 is supported upon an arm 24 which, as indicated by the curved arrow in Fig. 3, is pivotally attached to the base of the rigid support or casting I. It will be observed upon inspection of Fig. 1 that when the lamp 3 is locked in its socket the pin 23 on the pivoted support 24 is not necessarily in contact with the inner surface of the hole 2Ic in the lever 2 I.

The action of the above described system of levers is illustrated in Figs. 3 and 4. Thus, referring to Fig. 3, when the free end 2lb of the lever 2| is pressed down its opposite end 2 Ia bears against the underside of the annulus |2 and creates an approximately equal and opposite force which is transmitted through the L-shape arms 20 to the lower ends of the movable electrical leads I6 and I 6' so that the said leads are pulled downwardly against the force of their biasihg springs I1 and I1' and thus release the lower end of the lamp of this source of clamping action. As shown in Fig. 4, further downward movement of the pin is supported to swing inwardly, in the direca tion of the socket) and thereby to act as a lever of the lrst class. This lever action lifts the lowerV annulus I2 against the downward biasing force of the springs I3a etc. and raises the heads of the pins Illa etc. out of contact with the lamp-liange 8 so that the lamp 3 can easily be removed from its socket.

It will now be apparent that the present invention provides'a simple and convenient means for facilitating the removal of a pre-focused lamp from a lock-socket of the type incorporating spring-biased electrical contacts.

What is claimed is:

1. In a socket for a lamp having a base provided with an external electrical terminal, an electrical contact mounted for movement on said socket in register with said lamp, terminal, a spring for biasing said contact into engagement with said lamp terminal, and a compound lever, operatively connected to said contact and having a lost motion connection with said socket, for moving said contact out of engagement with said lamp terminal against the biasing force of said spring.

2. A socket for a lamp having a base and an electrical terminal on the exterior of said base, said socket comprising a hollow member for the reception of said terminal part of said lamp base, an electrical contact mounted for movement in register with said lamp terminal within said hollow member and extending to the exterior thereof, spring means mounted within said hollow member for biasing said electrical contact into engagement with said lamp terminal, and means including a link member pivotally mounted on said socket, a. handle member pivotally connected to said link, and a lever, pivotally connected to said handle, insulated therefrom, and pivotally connected to said contact, for moving said contact out of engagement with said lamp terminal against the biasing force of said spring means.

3. A socket for a lamp having a base, a ilange on said base and an electrical terminal on the free end of said base, said socket comprising a socketbase, a plurality of lamp retaining members projecting from said socket base in a position to engage said flange, a sub-base, an electrical contact movably mounted on said sub-base in a position to engage said electrical terminal, and lever means operatively connected to said lamp retaining members and to said electrical contact for moving said lamp retaining members into and out of engagement with said lamp flange and said electrical contact into and out of engagement with said lamp terminal.

4. A socket for a lamp having a base, a flange on said base and an electrical terminal on vthe free end of said base, said socket comprising an immovable apertured annulus upon which said tube ange is adapted to rest and a vertically movable annulus mounted in spaced relation with respect to said immovable annulus and through which the said free end of said lamp `base is adapted to extend, a plurality Vof lamp-retaining members mounted upon said movable annulus and extending through the apertures in said immovable annulus in a position to engage said ilange on said lamp base, spring means for exerting a clamping force upon said lamp flange through said lamp retaining members, an electrical contact for said lamp terminal mounted in said socket and removable with respect to said movable annulus, means for biasing said movable electrical contact -into engagement with sld `lamp terminal, and REFERENCES CITED lever means operatively connected to said lamp retaining members and to said electrical contact nghf fllgwgeerences are of record m the for relieving said lamp-Harige and said lamp-terminal of the forces applied thereto by said spring 5 UNITED STATES PATENTS means and said contact-biasing means. whereby Number Name Date.

to facilitate the removal of said lamp from said 2,110.13@ Doane et aL Mar. 3. .1933 r socket 2.426.424 Young Aug. 26, 1947 GEORGE H. GOBLE.

Certificate of Correction Patent No. 2,456,501. December 14, 1948. GEORGE H. GOBLE It is hereby certified that errors appear in the printed specication of the above numbered patent requiring correction as follows:

Column 3, line 17, for evert read exert; column 4, lines 73 and 74, for the Word "removable read movable;

and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case 1n the Patent Ofce.

Signed and sealed this 19th day of April, A. D. 1949.

THOMAS F. MURPHY,

Assistant Uommasoner of Patents. 

